Computational weld mechanics

计算焊接力学

• 批准号: 2922-2010
• 负责人: Goldak, John
• 金额: $ 2.04万
• 依托单位: Carleton University
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2011
• 资助国家: 加拿大
• 起止时间: 2011-01-01 至 2012-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=473645
• 关键词: Computational; weld; mechanics

In many in-situ weld repairs in thermal and nuclear power plants, petro-chemical and tar sands plants, the application of an elevated temperature post-weld heat treatment to reduce the hardness of the weld to acceptable levels is difficult and/or expensive. In those circumstances, the ASME Boiler and Pressure Vessel Code recommends the `half-bead' weld technique in which half of the filler metal deposited in each weld pass is removed by grinding before applying the next weld pass. A properly designed temper bead weld procedure can eliminate the very expensive grinding step of the half-bead weld technique. Performing the tests needed to qualifying a temper bead weld procedure can be expensive. The first objective of this proposal is to develop a computational model to automate the design of an optimal temper bead weld procedure for a given weld repair problem. The model will compute the transient temperatures and the evolution of the microstructure during welding and final hardness distribution for essentially all feasible variations of the welding process and then choose the optimal design and report the performance. The intent is to try to reduce the number of tests required to qualify the procedure to one. A second objective of this proposal is to automate the design of welding procedures to minimize the risk of hot cracking in welding austenitic stainless steels that are susceptible to hot cracking. Hot cracking in welds is a serious limitation in welding many stainless steel alloys used in applications that must resist corrosion and/or high temperatures. We propose to develop a holistic 3D transient model of hot cracking in welds that will couple our existing transient thermal analysis using an Ohji weld pool model with our existing synthetic microstructure evolution (but will add a phase field model with segregation and solute diffusion) with our existing transient thermo-visco-elasto-plastic stress and strain and strain-rate distribution model. It will also add single crystal plasticity. These models will reduce costs and improve the quality and reliability of welded structures.

在热电厂和核电厂、石油化工厂和沥青砂厂中的许多原位焊接修复中，应用高温焊后热处理以将焊接硬度降低到可接受的水平是困难的和/或昂贵的。在这种情况下，ASME锅炉和压力容器规范建议采用“半焊道”焊接技术，即在进行下一个焊道之前，通过研磨去除每个焊道中沉积的填充金属的一半。 一个适当设计的回火焊道焊接程序可以消除半焊道焊接技术的非常昂贵的研磨步骤。执行合格的回火珠焊程序所需的测试可能会很昂贵。这个建议的第一个目标是开发一个计算模型，自动化的最佳回火堆焊工艺的设计，为一个给定的焊缝修复问题。 该模型将计算焊接过程中的瞬态温度和微观结构的演变以及焊接工艺基本上所有可行变化的最终硬度分布，然后选择最佳设计并报告性能。 目的是尝试将鉴定程序所需的测试数量减少到一个。 本提案的第二个目标是自动设计焊接程序，以最大限度地减少焊接奥氏体不锈钢中易产生热裂纹的风险。焊接中的热裂纹是在必须耐腐蚀和/或高温的应用中使用的许多不锈钢合金的焊接中的严重限制。 我们建议开发一个整体的3D瞬态模型的焊缝热裂纹，将我们现有的瞬态热分析与我们现有的合成微观结构的演变（但会增加一个相场模型与偏析和溶质扩散）与我们现有的瞬态热粘弹塑性应力和应变和应变率分布模型的Ohji焊池模型。它还将增加单晶的可塑性。这些模型将降低成本，提高焊接结构的质量和可靠性。